1. Field of the Invention
The present invention relates to a method, system, and program for selecting storage clusters to use to access storage.
2. Description of the Related Art
Host systems in a storage network may communicate with a storage controller through multiple paths. The storage controller may be comprised of separate storage clusters, where each storage cluster is capable of accessing the storage and provide redundancy to access the storage. If a storage cluster fails, then the host may failover to using the other storage cluster to access the storage.
In certain systems, if a storage cluster receives Input/Output (I/O) requests to a storage location, such as a track or volume, that are the subject of I/O requests pending at another storage controller, then the storage cluster receiving the I/O requests will transfer them to the other storage controller to minimize the extent to which different storage clusters apply I/Os to a same storage location. Data consistency errors may result if separate storage controllers write data in an inconsistent manner to a same storage location. This process where a storage cluster transfers I/O requests to another storage cluster to consolidate I/O requests to a same storage location at one storage cluster requires that I/O requests be quiesced to the clusters involved in the transfer during the time that the transfer occurs. This transfer of I/O requests and writes between storage controllers degrades the storage controller performance.
There is a need in the art for improved techniques for managing how hosts may select which of multiple storage clusters to use to access a storage.